Closed-loop recycling of C&amp;D waste: Mechanical properties of concrete with the repeatedly recycled C&amp;D powder as partial cement replacement

Kim, Jeonghyun; Jang, Haneol

doi:10.1016/j.jclepro.2022.130977

Cited by 78 publications

(17 citation statements)

References 38 publications

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“…At 56 days of age, the RC specimens after the testing described in Section 2.3 were compressed with a hydraulic universal testing machine and crushed into large pieces (approximately 50 to 100 mm in length), and these concrete fragments were crushed into sizes (up to 25 mm) suitable for concrete production using the Los Angeles ball mill. By combining mechanical and manual sieving, three recycled concrete materials with different size fractions were obtained: RCA with a size of 4.75–25 mm, RFA with a size of 0.15–4.75 mm, and RP smaller than 0.15 mm [ 32 ]. Table 2 shows the properties of recycled aggregates along with natural ones.…”

Section: Methodsmentioning

confidence: 99%

“… RPC-replacement ratio: Concrete made with NCA, NFA, OPC, and RP that replaces OPC in a certain proportion (10%, 20%, and 30%). Test results for RPC were adopted from the previous study of the author [ 32 ]. RCFAC-replacement ratio: Concrete made by replacing both NCA and NFA with RCA and RFA in a certain percentage (30%, 60%, and 100%).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

2022

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For complete utilization of construction and demolition (C&D) waste, an investigation of all size fractions of C&D waste generated during the recycling process should be conducted. In this work, the effects of three recycled concrete materials with different sizes (recycled coarse aggregate (RCA) with a size of 4.75–25 mm, recycled fine aggregate (RFA) of 0.15–4.75 mm, and recycled powder (RP) smaller than 0.15 mm) produced from concrete waste on the fresh and hardened mechanical properties of concrete were evaluated. The replacement ratios of natural coarse and fine aggregates by RCA and RFA were 30, 60, and 100%, and those of ordinary Portland cement for RP were 10, 20, and 30%. The results showed that the concrete properties deteriorated with increasing replacement ratio regardless of the type of recycled materials. The properties were reduced in the order of the use of RFA, RCA, and the simultaneous use of RCA and RFA. In addition, concrete with 30% RP showed lower mechanical strength than concrete with 100% RCA and 100% RFA. However, all concretes could be applicable for structural purposes under different environmental exposure conditions. In particular, concretes with 10% RP and 20% RP showed better cost-benefits compared to natural aggregate concrete with 100% ordinary Portland cement. These promising findings provide valuable initiatives for the effective and complete recycling of C&D waste.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

2022

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“…Construction and demolition (C&D) waste pollution and shortage of coarse aggregate have become increasingly serious problems nowadays [1,2]. In this case, the emergence of recycled aggregate concrete (RAC) helps reduce the pollution of C&D waste and contributes to the sustainable development of the construction industry [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Compressive Performance of Fiber Reinforced Recycled Aggregate Concrete by Basalt Fiber Reinforced Polymer-Polyvinyl Chloride Composite Jackets

Zhai¹,

Liu²,

Liu³

et al. 2023

Journal of Renewable Materials

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The development of recycled aggregate concrete (RAC) provides a new approach to limiting the waste of natural resources. In the present study, the mechanical properties and deformability of RACs were improved by adding basalt fibers (BFs) and using external restraints, such as a fiber-reinforced polymer (FRP) jacket or a PVC pipe. Samples were tested under axial compression. The results showed that RAC (50% replacement of aggregate) containing 0.2% BFs had the best mechanical properties. Using either BFs or PVC reinforcement had a slight effect on the loadbearing capacity and mode of failure. With different levels of BFs, the compressive strengths of the specimens reinforced with 1-layer and 3-layer basalt fiber reinforced polymer (BFRP) increased by 6.7%-10.5% and 16.5%-23.7%, respectively, and the ultimate strains increased by 48.5%-80.7% and 97.1%-141.1%, respectively. The peak stress of the 3-layer BFRP-PVC increased by 42.2%, and the ultimate strain improved by 131.3%, relative to the control. This reinforcement combined the high tensile strength of BFRP, which improved the post-peak behavior, and PVC, which enhanced the structural durability. In addition, to investigate the influence of the various constraints on compressive behavior, the stress-strain response was analyzed. Based on the analysis of experimental results, a peak stress-strain model and an amended ultimate stress-strain model were proposed. The models were verified as well; the result showed that the predictions from calculations are generally consistent with the experimental data (error within 10%). The results of this study provide a theoretical basis and reference for future applications of fiber-reinforced recycled concrete. KEYWORDSBasalt fiber reinforced polymer; polyvinyl chloride; recycled aggregate concrete; axial compression performance; stress-strain relationships; stress-strain model Nomenclature f 0 l Lateral confining pressure of actively confined concrete (MPa) f lp Lateral confining pressure of PVC confined concrete (MPa) f lf Lateral confining pressure of BFRP confined concrete (MPa) E pvc Elastic modulus of PVC (MPa) e pvc Mono-axial tensile strain of PVC t pvc Thickness of PVC material (mm) E frp Elastic modulus of FRP (GPa)

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“…Previous studies demonstrated that the RCF exhibited potential reactivity, which can be used for new concrete production [ 21 ]. However, the workability, strength, and durability of concrete containing RCF would significantly decrease due to the high porosity and low reactivity of RCF [ 22 , 23 , 24 ]. Therefore, only a minimal amount of RCF can be utilized, and the rest is disposed of by landfilling and dumping, failing to take full advantage of waste resources and causing environmental and groundwater pollution [ 2 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Accelerating the Reaction Kinetics of Na2CO3-Activated Slag Mortars by Calcined Recycled Concrete Fines

Wang

et al. 2022

Materials

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Sodium carbonate (Na2CO3), an environmentally friendly activator, has been shown to have vast potential for the development of sustainable alkali-activated slag mortars. However, Na2CO3-activated slag mortars exhibit a delayed reaction process and limited early-age strength development, restricting their wider application. In this work, the recycled concrete fines were calcined at a temperature of 800 °C for 1 h and then used as an auxiliary activator to improve the reaction kinetics of Na2CO3-activated slag mortars. The impact of the calcined recycled concrete fines (CRCF) dosage and Na2CO3 concentration on the compressive strength, hydration kinetics, and phase assemblage of mortars was evaluated. The results show that CRCF can react directly with Na2CO3 in the early stages, swiftly removing the CO32− in aqueous solution and providing an alkaline environment suitable for the dissolution of slag. This promotes the development of C-(A)-S-H, hydrotalcite, hemicarbonate, and monocarbonate. The hydration process and strength-giving phase of mortars can be improved further, as an increase in Na2CO3 concentration increases the initial alkaline content. Additionally, the most remarkable compressive strength value of 39.2 MPa was observed at 28 days in the mortar with 6% sodium oxide equivalent (Na2O-E) of Na2CO3 and 15% CRCF because of the synergistic effect of CRCF and Na2CO3.

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Closed-loop recycling of C&D waste: Mechanical properties of concrete with the repeatedly recycled C&D powder as partial cement replacement

Cited by 78 publications

References 38 publications

An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

Compressive Performance of Fiber Reinforced Recycled Aggregate Concrete by Basalt Fiber Reinforced Polymer-Polyvinyl Chloride Composite Jackets

Accelerating the Reaction Kinetics of Na2CO3-Activated Slag Mortars by Calcined Recycled Concrete Fines

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